1x6pin connector+6950?

I have a HEC 600Watt and the sig rig, I was planning to get a 6950 1GB, I really don't have the cash to get a new PSU, so either I get a 6850 and save some money or the 6950 1GB.
Question is: Will my HEC power the 6950 up? Also, should I worry about the dual 6pin connectors the 6950 uses? Or an adapter will solve that?